This is a box insert I made for Project L, after my wife commented that she didn't like how all the pieces were in small plastic bags.
The main box has 2 slots each for the black and white cards, and the pieces are separated into 2 boxes that go on top of each other in the insert. Each piece box has divided trays for each piece. The piece labels are raised so if you have a multi-color printer you can match the colors of the pieces.
Tolerances are a bit tight for the insert fitting into the cardboard box. It'll fit, but it might be a chore to get it out if you need to. The dividers in the piece boxes may feel flimsy if you don't use enough walls, I recommend 4, though YMMV based on your other print settings.
Ghost Piece Expansion Box Insert: https://www.printables.com/model/800701-project-l-ghost-piece-expansion-box-insert-organiz
The author marked this model as their own original creation.